The present invention relates generally to interface units for testers that test electrical characteristics of IC (Integrated Circuit) devices and other semiconductor devices. More particularly, the present invention relates to a tester interface unit for providing electrical connection between a contact ring and a motherboard, and a method of connecting the tester with a semiconductor device to be tested.
In order to ship IC devices with performance and quality assurances as final products, it is generally necessary to extract some or all of the IC devices and examine predetermined electrical characteristics of the extracted devices in manufacturing and test stages. Normally, the electrical characteristics of the IC devices are examined by so-called IC testers. In many cases, the IC testers perform a probe test for examining IC devices formed on a semiconductor wafer prior to a final test step. For examination of the IC devices on the semiconductor wafer, a special test device called a xe2x80x9cprobe device (or probe card)xe2x80x9d is required which connects the IC devices to the IC tester. Each of the ordinary-type probe devices operates in a so-called cantilever fashion. Namely, each of these probe devices has a plurality of tungsten needles manually soldered onto a printed circuit board and projecting obliquely from the printed circuit board, and the obliquely-projecting tungsten needles are resiliently pressed against bonding pads of the IC devices. Therefore, the number of the IC devices that can be examined simultaneously depends greatly on the technology for manufacturing the probe device.
In recent years, the number of IC devices capable of being examined simultaneously has been progressively increasing, such as 16, 32 and 64. As the number of IC devices capable of being examined simultaneously increases there arises a need to reliably connect signal lines corresponding to 1,000 to 3,000 pins between the probe device and the tester, not to mention a need for a technique of fixing the needles with high accuracy. The probe devices today generally include a signal-line-connecting area that is located off and around the outer periphery of a central needle-fixing area, and thus it has become extremely difficult to form, in that signal-line-connecting area, a wiring pattern for supplying electric signals to 3,000 or more pins. Further, because the wiring pattern is connected with the signal lines by soldering, there would arise the problems that gold-plated pads of the IC devices are smudged or stained by a flux used in the soldering and a leakage current is produced between the pins by the flux.
Japanese Patent Laid-open Publication No. HEI-8-139142 discloses using a POGO pin ring in the form of an annular board. The POGO pin ring disclosed in the publication has a large number of POGO pins on opposite surfaces thereof. The POGO pins on one of the two surfaces are electrically connected with those on the other surface in a one-to-one relation. The one surface of the POGO pin ring is brought into contact with a performance board associated with a test head while the other surface of the POGO pin ring is brought into contact with a probe card, so that an electrical connection is achieved between the test head and the probe card. In this case, the distance or interval between the test head and the probe card is fixedly defined by the thickness of the POGO pin ring, and thus the tester is unavoidably fixed in construction, which would result in poor operability of the tester.
It is therefore an object of the present invention to provide an interface unit for a tester which can effectively avoid inconveniences encountered in connecting signals lines regardless of an increase in the number of simultaneously-tested IC devices and thereby achieves highly-reliable connection between the signal lines.
In order to accomplish the above-mentioned object, the present invention provides an interface unit for a tester which comprises: a contact board having a large number of contact terminals provided on one surface thereof, and sockets provided on another surface thereof and electrically connected with the contact terminals; a motherboard having a large number of wires to be connected to the contact terminals of the contact board, and a large number of sockets electrically connected with the wires; and a large number of connecting cables each having two plugs provided at opposite ends thereof. The plug provided at one end of each of the connecting cables is removably inserted in one of the sockets of the contact board and the plug provided at another end of each of the connecting cables is removably inserted in one of the sockets of the motherboard, so that the connecting cables electrically connect the contact terminals of the contact board with the wires of the motherboard.
The tester interface unit is used for providing electrical connection between a test control section and a probe section of a tester for an IC or other semiconductor device. The wires of the motherboard are connected to the test control section and the contact terminals provided on the one surface of the contact board are placed in contact with contact terminals of the probe section. The probe section is a probe card having the above-mentioned contact terminals on one surface thereof and contact needles, such as tungsten needles, on the other surface thereof, and the contact terminals of this probe section are electrically connected with the contact needles. When performing a test, the contact needles of the probe section are placed in contact with predetermined terminals of the device to be tested such as a semiconductor wafer, semiconductor device or IC.
The contact board is a contact ring having an annular shape, and the contact terminals provided on its one surface facing the probe card are resiliently movable contact pins such as POGO pins. This contact ring has, on the other surface, press-fitting sockets electrically connected with the POGO pins. The motherboard also has sockets that are similar in construction to the press-fitting sockets of the contact ring. By press-fitting plugs at opposite ends of connecting cables in desired ones of the sockets of the contact board and motherboard, the contact terminals (POGO pins) of the contact ring and the contact terminals of the motherboard are electrically connected with each other. Because the contact ring and the motherboard are electrically connected with each other only by the press-fit engagement between the plugs and the sockets, there are encountered no inconveniences that would result from the conventional soldering-based connection. Such plugs and sockets are preferred in that they can be firmly press-fitted with each other with increased reliability. For examples, each of the connecting cables is a coaxial cable including mold terminal sections at opposite ends thereof, and each of the mold terminal sections has at least two plugs projecting therefrom. Although it is preferable that the contact terminals provided on the one surface of the contact board be POGO pins as noted above, any other contact terminals than the POGO pins may be employed.